Abingdon Coal Member or Bed
Nelson, W.J., 2020, Pennsylvanian Subsystem in Illinois: Illinois State Geological Survey Bulletin (in press).
Edited and figures drafted by Jennifer M. Obrad.
Weller et al. (1942, p. 1589) reported that the “commonly embryonic and thin” Abingdon cyclothem persistently lies between the Greenbush and Colchester Coals in western Illinois, especially southern Knox and northern Fulton Counties. These authors also recognized the Abingdon cyclothem in southern Iowa. From the top downward, the cyclothem comprises shale that is gray in Illinois and red and platy in Iowa, thin and discontinuous limestone, coal ranging from a streak to a few inches (ca.5–10 cm) thick, underclay, and sandstone. Subsequently, Kosanke et al. (1960) formally designated the Abingdon Coal Member (of the Spoon Formation).
Abingdon is a city of about 3,200 people situated in southwestern Knox County, Illinois, about 10 mi (16 km) south of Galesburg. The name was transferred from Abingdon, Maryland, which, in turn, was named after Abingdon in Oxfordshire, United Kingdom (Callary 2009).
Kosanke et al. (1960) and Willman et al. (1975) erroneously attributed the Abingdon Coal to Culver (1925, p. 75–76), who wrote, “A small amount of coal is spasmodically mined from the Abingdon field [in Knox County, Illinois]. The extent of the coal is not well known, but recent drilling indicates that it extends northward to within three miles [4.8 km] of Galesburg and extends eastward somewhat beyond Spoon River. It is normally about two feet [60 cm] thick, without partings, and of fair quality. It is bright and hard and contains lenses and balls of pyrite. The roof is shale, black and fissile, and overlain by another shale, non-gritty, gray in color, known as ‘soapstone’. The section here is similar to that of the Colchester coal.” Subsequent investigations, especially Smith and Berggren (1963), demonstrate that the “Abingdon coal” of Culver (1925) is indeed the Colchester. Weller et al. (1942) did not cite Culver (1925) and were probably unaware of his previous discussion of coal at Abingdon.
Weller et al. (1942, p. 1589) observed that the Abingdon cyclothem and coal are well exposed about 4 mi (6 km) east of Abingdon along a southwest tributary of Brush Creek near the center of sec. 6, T 9 N, R 2 E, Knox County, on the De Long 7.5 quadrangle. Not previously published, this section is presented here in graphic form based on field notes made by H.R. Wanless in August of 1929 (Figure 4-17).
Weller et al. (1942).
The present condition of the outcrop is unknown.
None has been designated. Wanless (1957) published a number of outcrop sections that could potentially suffice.
In western Illinois, the Abingdon is thin coal or carbonaceous shale that rests on rooted underclay above the Isabel Sandstone and is overlain by shale or mudstone (Figure 4-9). The Abingdon Coal is hereby extended into southeastern Illinois for what Jacobson (1987, 1993) called the “upper split of the Dekoven Coal” (Figure 4-12). As presently recognized, the Abingdon merges with the older Greenbush Coal to form the Dekoven Coal, and the Dekoven in turn merges with the Davis to produce the Seelyville Coal Member.
Extent and thickness
In western Illinois and southeastern Iowa, the Abingdon ranges from a streak to about 16 in. (39 cm) thick (Weller et al. 1942; Wanless 1957). The coal has no economic significance and has not been mapped. The coal is probably absent far more widely than it is present.
In southern Illinois, the thickness of the Abingdon has been mapped only in Gallatin and Saline Counties (Jacobson 1993, figure 9). Jacobson’s map shows that the coal is commonly between 1.5 and 3.5 ft (45 to 107 cm) thick and locally exceeds 4.5 ft (137 cm).
The Abingdon is generally bright-banded coal, grading to carbonaceous shale where it pinches out. The coal rests on underclay that is weakly to moderately well developed. Olive-colored, blocky to massive structures, slickensides, roots, and siderite nodules are developed in some sections. Overlying the Abingdon in western Illinois is a thin interval of gray, olive, or greenish gray shale or mudstone, grading upward to the underclay of the Colchester Coal. In southern Illinois, a much thicker succession separates the Abingdon from the Colchester. This typically coarsens upward from dark gray, sideritic shale in the lower part to lighter gray siltstone or sandstone in the upper part.
Both contacts are sharp or gradational through a thin interval.
Well log characteristics
Typical for coal.
Peppers (1970) described fossil spores from two samples of coal believed to be Abingdon, from drill cores in Edgar and LaSalle Counties, Illinois. Not surprisingly, the flora was similar to that of the Colchester, although significant differences were noted.
Age and correlation
Although the position of the Abingdon in the Midcontinent Basin is closely constrained, no exact equivalent has been identified (Figure 4-12).
Environments of deposition
Like most named Middle Pennsylvanian coal seams in this basin, the Abingdon evidently represents a widespread coastal peat swamp.
As a component of the Dekoven Coal, the Abingdon has been mined in southeastern Illinois, and resources remain.
- Callary, E., 2009, Place names of Illinois: Urbana, University of Illinois Press, 425 p.
- Culver, H.E., 1925, Coal resources of District III (western Illinois): Illinois State Geological Survey, Cooperative Mining Series Bulletin 29, 128 p.
- Jacobson, R.J., 1987, Stratigraphic correlations of the Seelyville, Dekoven, and Davis Coals of Illinois, Indiana, and western Kentucky: Illinois State Geological Survey, Circular 539, 27 p. and 2 pls.
- Jacobson, R.J., 1993, Coal resources of the Dekoven and Davis Members (Carbondale Formation) in Gallatin and Saline Counties, southeastern Illinois: Illinois State Geological Survey, Circular 551, 41 p., 5 pls.
- Kosanke, R.M., J.A. Simon, H.R. Wanless, and H.B. Willman, 1960, Classification of the Pennsylvanian strata of Illinois: Illinois State Geological Survey, Report of Investigations 214, 84 p. and 1 pl.
- Peppers, R.A., 1970, Correlation and palynology of coals in the Carbondale and Spoon Formations (Pennsylvanian) of the northeastern part of the Illinois Basin: Illinois State Geological Survey, Bulletin 93, 173 p.
- Smith, W.H., and D.J. Berggren, 1963, Strippable coal reserves of Illinois, Part 5A, Fulton, Henry, Knox, Peoria, Stark, Tazewell, and parts of Bureau, Marshall, Mercer, and Warren Counties: Illinois State Geological Survey, Circular 348, 59 p., 4 pls.
- Wanless, H.R., 1957, Geology and mineral resources of the Beardstown, Glasford, Havana, and Vermont Quadrangles: Illinois State Geological Survey, Bulletin 82, 233 p.
- Weller, J.M., H.R. Wanless, L.M. Cline, and D.G. Stookey, 1942, Interbasin Pennsylvanian correlations, Illinois and Iowa: American Association of Petroleum Geologists Bulletin, v. 26, p. 1585–1593.
- Willman, H.B., E. Atherton, T.C. Buschbach, C. Collinson, J.C. Frye, M.E. Hopkins, J.A. Lineback, and J.A. Simon, 1975, Handbook of Illinois stratigraphy: Illinois State Geological Survey, Bulletin 95, 261 p.
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